Anti-corrosive salt



United States Patent 3,384,590 ANTI-CORROSIVE SALT Russell A. Eversole,Excelsior, and Young J. Lee, Minneapolis, Minm, assignors to Cargill,Incorporated, Bloomington, Del., a corporation of Delaware N0 Drawing.Filed Nov. 25, 1964, Ser. No. 413,995 16 Claims. (Cl. 252-70) ABSTRACTOF THE DISCLOSURE A salt composition for de-icing including a de-icingsalt and minor but effective amounts of an alkali metal chromate ornitrite anodic passifier and an organic compound cathodic passifierhaving an amino nitrogen atom and an alkyl radical of from 8 to 24carbon atoms.

This application is a continuation-in-part of application Ser. No.336,861, filed Jan. 10, 1964, and now abandoned.

This invention relates generally to an improved salt composition, andmore particularly relates to a salt composition for de-icing havingimproved anti-corrosive characteristics. The invention also relates to amethod of manufacturing a salt composition containing such anticorrosiveagents.

The corrosive effect of an aqueous solution of soluble salts,particularly halogen salts such as sodium chloride and calcium chloride,on metal surfaces is well known. Halogen salts such as sodium chlorideand calcium chloride are particularly useful as freezing pointdepressants for de-icing, e-.g., for melting ice and snow on streets andsidewalks. However, the aqueous sodium chloride and calcium chloridesolutions that are formed when these salts are employed to melt ice andsnow are corrosive and when these salt solutions are splashed upon theunderside of a car, corrosion problems occur.

Various agents, such as alkali hexameta-phosphates and alkali chromates,have been mixed with halogen salts in an attempt to reduce the corrosiveeffect of these salts, when employed as ice melting compounds. However,at tempts to reduce the corrosive effect of halogen salts have beengenerally unsuccessful and corrosion usually results when an aqueoussolution of a halogen salt contacts metal surfaces.

It is a principal object of the present invention to provide a saltcomposition for de-icing having improved anticorrosivecharacteristics.It is another object to provide a soluble halogen salt composition whichhas improved anti-corrosive characteristics in an aqueous medium. Anadditional object is to provide a method of manufacturing a saltcomposition having improved anti-corrosive characteristics. Yet anotherobject of the invention is to provide an improved salt compositioncontaining anticorrosive agents for preventing corrosion of metallicsurfaces in contact with an aqueous solution of the salt. A furtherobject is to provide an anti-corrosive salt composition which does notsegregate upon handling.

These and other objects of the invention are more particularly set forthin the following detailed description.

Generally, the present invention comprises a Water soluble saltcomposition of improved anti-corrosive characteristics containingsuitable anti-corrosive agents which provide binary passivation to ametallic surface in contact with an aqueous solution of the salt. Morespecifically, the present invention is directed to a salt compositionhaving improved anti-corrosive properties comprising, a water solublesalt containing minor, but effective, amounts of an anodic passifierselected from the group consisting of alkali metal chromates, alkalimetal nitrites and mixtures thereof, and a cathodic passifier which maybe defined 3,384,596 Patented May 21, 1968 ice , compounds containing anamino nitrogen atom and an alkyl radical having from 8 to 24 carbonatoms or mixtures thereof. The cathodic passifier exhibits a strongpositive charge in solution. For purposes of the present invention theterm cationic surface active agent includes those compounds that aresometimes referred to as amphoteric surface active agents, e.g.,compounds which may be either cationic or anionic. Also, the term aminonitrogen atom is intended to include a quaternary nitrogen atom.Further, the term alkali metal chromates is intended to include bothalkali metal chromates and alkali metal dichromates.

Cationic surface active agents which include an amino nitrogen atom anda long chain alkyl radical, and which exhibit a significant positivecharge in solution include the following general groups of organiccompounds:

(1) N-alkyl-diamines R1 RN(CHz)nN (2) N-alkyl-triamines R1RN(CH2)nN(CH2)mN (3) N-v alkyl oxypropyl-diamines R1 RO(CH2)3N(CH2)nN(4) N-'y alkyl oxypropyl-triamines Rx RO(CH2)aNH(CH2)nNH(CH2) N (5)'Nalkyl B amino propionic acids 'RNH C'Hz 2COOH] q (6) 'N-y alkyloxypropyl-B amino-propionic acids RO(CH N'HHCH OOOH], (7) Alkylquaternary ammonium compounds (Rh N z)u (8) Alkyl oxypropyl quaternaryammonium compounds [R0 (CH1) gl N- X- (9) Alkyl diethanol benzylqua-ternary ammonium compounds (HO CHzCHzlZ I$CH2COH5, x-

(10) N-,@ alkyl amidoethyl-ethyl-ene amines .3 i112) l-ethyl, 2-alkylimidazolines where:

.R=an alkyl radical of from 8 to 24 carbon atoms R =hydrogen or a shortchain alkyl radical of from 1 to 6 carbon atoms R =hydrgen or a shortchain alkyl radical of from 1 to 6 carbon atoms R =a short chain alkylradical of from 1 to 6 carbon atoms X=a salt forming radical Z=an aminoor hydroxyl radical n=2 to and the sum of o and p is 4 q=ll or 2 r=0 or1 and the sum of q and r is 2.

It is understood that the cat-ionic surface active agents may be presentin the form of soluble salts, and in some instances that salt form ispreferred.

Specific examples of cationic surface active agents which are suitablecathodic passifiers include N-alkyletheylene diamine; N-alkyl-diethylenetriamine; N-alkyl- 1,3 propylene diamine; N-alkyl-dipropylene triamine;N'y alkyl oxypropyl-N-alkyl-ethylene diamine; N-y alkyloxyp'ropropyl-ll,3 propylene diamine; N-y alkyl oxypropyl-dipropylenetriamine; N-alkyl-{i amino propionic acid; N-alkyl-fl iminodipropionicacid; N-y alkyl oxypropyl-B aminopropionic acid; N-'y alkyl oxypropyl-[iiminodipropionic acid; alkyl trimethyl ammonium chloride; dialkyldimethyl ammonium chloride; mono, di and tri gamma alkyl oxypropylammonium chloride; alkyl diethanol benzyl ammonium chloride; N-p alkylamid-oethyl-ethylene diamine; N-B alkyl amidoethyl-ethylene diamine; N-Balkyl amidoethyl-ethanol amine; N-alkyl- N-ethyl ethanol amine;'l-ethanol amine, 2-alkyl, imidozoline; l-ethanol, Z-alkyl, imidazoline,or salts thereof.

The alkyl radical of the cationic surface active agent may be any alkylhaving from 8 to 24 carbon atoms. Preferred alkyl radicals include thealkyl radicals obtained from coconut oil, tallow, soybean oil, tall oil,and other triglycerides, as well as the alkyl radicals obtained fromlong chain carboxylic acids.

'Binary passivation of a metallic surface in contact with a watersoluble corrosive salt occurs when the salt solution contacting themetallic surface contains an anodic passifier and a cathodic passifier.As used herein, passivation of a metallic surface occurs when themetallic surface substantially resists oxidation in an environment wherethere is a large decrease in the free energy of the metal when the metalis oxidized to a metallic oxide, i.e., when corrosion takes place. Thus,when a metal is passivated, the metal is made resistant to corrosion.

Corrosion of a metal occurs when the metal is oxidized to theappropriate metallic oxide. In general, the oxidation of a metal is anelectrochemical reaction, electric currents flowing between randomanodic areas and cathodic areas "on the surface of the metal. Binarypassivation includes the use of a soluble cathodic passifier having astrong positive charge in solution which is attracted to the negativecathodic areas on the metallic surface, and the use of a soluble anodicpassifier which carries a strong negative charge and is attracted to thepositively charged anodic areas on the metallic surface.

The cathodic passifier is a soluble compound which has a strong positivecharge in solution and which has good film forming properties whichcause the cathodic passi-fier to form a continuous molecular film overthe relatively large cathodic areas of the metallic surface. The filmformed by the cathodic passifier serves as a galvanic barrier andprevents the corrosive salt solution from contacting the cathodic areasof the metallic surface.

The anodic passifier is desirably a soluble ion having a strong negativecharge in solution. The anodic passifier should be readily reducible andshould preferentially react with partially oxidized metallic ions andnot with free metallic ions. Additionally, the reduction product oi theanodic passifier is preferably insoluble and is retained at the surfaceof the anodic areas along with the insoluble metallic oxide film formedby corrosion of the metallic surface to form a galvanic barrier at theanodic areas of the metallic surface. In this connection, while nitratesare suitable as anodic passifiers, the reduction product of the nitrateion is ammonia which is soluble and is not retained in the metallicoxide film formed at the surface of the anodic areas.

Thus, binary passivation is used to describe an anticorrosive systemwherein selective anti-corrosive agents are combined, certain of theanti-corrosive agents passivating the cathodic areas of the metallicsurface and other of the anti-corrosive agents passivating the anodicareas of the metallic surface. In some instances it may be desirable toutilize mixtures of two or more of the anodic passifiers and/ orcathodic passifiers.

The binary passivation of metallic surfaces is of particular importancewhere a soluble halogen salt, for example sodium chloride or calciumchloride, comes in contact with metallic iron. One of the major uses ofsoluble halogen salts is as a freezing point depressant to effectde-icing in the melting of ice and snow from streets and sidewalks. Whensodium chloride or calcium chloride is used as an ice melting salt thesodium chloride and/ or calcium chloride solution thus formed issplashed upon the under surface of vehicles traveling along the road.The presence of the chloride salt solution in contact with the undersurface of the vehicle causes pitting and rusting of the body of thevehicle.

While the manner in which the invention performs is not altogetherunderstood, the following may occur. When an aqueous solution contactsan iron containing surface, the iron in contact with the water andoxygen is oxidized to ferrous hydroxide at the surface of the metal.Ferrous hydroxide is soluble in water to the extent of a fraction of amilligram per parts of water, and is generally considered insoluble.However, ferrous hydroxide is the most soluble of the various ironoxides that might be formed, and is substantially more soluble thanthose iron oxides which have a cubic crystalline structure, eg. gammaferric oxide, magnetite and the like. In the absence of other solubleions in the aqueous solution, the ferrous hydroxide is further oxidizedto an intermediate non-cubic iron oxide which is more insoluble thanferrous hydroxide but which is more soluble than the cubic iron oxides.When the aqueous solution does not contain additional soluble ions, itdoes not appear that significant amounts of the cubic iron oxides areformed. An insoluble film of corrosion products is formed upon themetallic iron surface which tends to prevent further corrosion of theiron surface. However, if chloride ions are also present in the aqueoussolution, they react with the metallic iron surface to form ferrouschloride and ferric chloride, both of which are highly soluble in water.The removal of these soluble chloride compounds from the iron surfacecontinuously exposes fresh iron to corrosion and causes erosion andpitting of the surface. The reaction between the iron and chloride ionsto form soluble ferrous chloride and ferric chloride interferes with theformation of the insoluble iron oxides and substantially reduces theformation of the insoluble film of corrosion products on the ironsurface.

It has been discovered that the corrosion of a metallic surface by anaqueous halide salt solution, e.g., sodium chloride, can besubstantially prevented by the combined use of an anodic passifier and acathodic passifier. For example, a de-icing salt composition containinga sodium chromate anodic passifier and a N-coconut-1,3 propylene diaminediacetate cathodic passifier substantially prevents corrosion of ametallic iron surface in contact with an aqueous solution of theanti-corrosive salt.

The sodium chromate anodic passifier is attracted to the anodic areas ofan iron containing surface due to its strong negative charge. The sodiumchromate reacts preferentially with ferrous hydroxide as opposed to themetallic iron, and promotes the oxidation of the ferrous hydroxide togamma ferric oxide as opposed to the more soluble intermediate ironoxides. It is believed that the sodium chromate is reduced to chromicoxide which is retained in the insoluble gamma ferric oxide film formedupon the surface of the anodic areas and aids in the formation of agalvanic carrier at the anodic areas of the iron surface. Thus, in thepresence of an anodic passifier, the film of corrosion products formedat the anodic areas of the iron surface is substantially more insolubleand the corrosion of the iron surface by the chloride ions is reduced.

The N-coconut-1,3 propylene diamine diacetate is attracted to thenegative cathodic areas of the iron surface where it forms a molecularfilm, i.e., a galvanic and physical barrier, over the cathodic areas ofthe surface of the iron. The formation of galvanic barriers at both thecathodic and anodic areas of the metallic surface substantially reducesthe flow of current driving the electrochemical corrosive reactions, anddiminishes contact of the chloride ions, moisture, and oxygen with theiron surface, thereby reducing the corrosion of the metallic surface.

An anti-corrosive salt composition may be manufactured by mixing agranular salt, e.g., sodium chloride or calcium chloride, with effectiveamounts of an anodic passifier and a cathodic passifier. Theanti-corrosive salt should be manufactured in a manner so that theanodic passifier and cathodic passifier are not separated from the saltdue to dusting or segregation during handling or transportation of thesalt. In order to prevent dusting and segregation it has been found thateither the anodic passifier or cathodic passifier may be admixed withthe salt in liquid form, if so desired. Generally, the cathodicpassifier, e.g., a N-alkyldiamine salt, is mixed with the granular saltin liquid form since it will normally be a liquid.

A granular anti-corrosive salt, e.g., rock salt, may be manufatured byforming an intimate dray mixture of rock salt and an anodic passifier.,e.g., sodium chromate. The anodic passifier should be employed in aneffective amount which retards corrosion of the metallic surface whencombined with a particular cathodic passifier. Generally, as little as0.05 percent by Weight of the granular salt of the anodic passifier willbe an effective amount, although in some instances, lesser amounts maybe employed. There is no apparent upper limit to the amount of anodicpassifier that may be utilized. However, when the anodic passifier isemployed in amounts in excess of one percent by Weight of the granularsalt, the increase in the amount of anodic passifier generally does notprovide proportionally increased protection against corrosion.

An anti-caking agent such as sodium ferrocyanide is desirably includedin the dry mixture of granular salt and anodic passifier. Theanti-caking agent may be employed in an amount of about 0.05 percent byweight of the salt, or in any suitable amount which will prevent cakingthereof.

The dry mixture of salt, anodic passifier and anticaking agent then maybe sprayed with an aqueous solution of the cathodic passifier, e.g.,N-coconut-1,3 propylene diamine diacetate, .and the mixture is suitablyagitated to insure even distribution of the cathodic passifier solutionover the surface of the salt. The cathodic passifier forms a film on thesurface of the salt granules and acts as a binder for the anodicpassifier and anticaking agent, thus preventing segregation or siftingof these materials during handling and transportation of theanti-corrosive salt. The cathodic passifier is employed in an amountwhich is effective to retard corrosion of the metallic surface incombination with the anodic passifier. Generally, the cathodic passifiersolution is of a suitable concentration to provide at least 0.01percent, preferably 0.5 percent by weight of the granular salt of thecathodic passifier. As with the anodic passifier, there is no apparentupper limit to the amount of cathodic passifier that may be employed,and up to about two percent by weight or more of the granular salt ofthe cathodic passifier may be utilized if desired.

It is advantageous to include a dispersing agent in the aqueous solutionof the cathodic passifier that is sprayed on the salt. The dispersingagent may be employed in an amount suitable to aid in dispersing thecathodic passifier and .01 percent to about 0.1 percent by weight of thesalt of a nonionic surface active agent sold under the tradename Makon10 has been found to be particularly suitable. Other dispersing agentsthat may be employed include Triton X-200, an anionic surface activeagent; Triton X-l00, a nonionic surface active agent and Triton QS-IS,an amphoteric surface active agent. The use of other suitable dispersingagents is also contemplated.

A suitable dye may also be included in the cathodic passifier solutionin order that the anti-corrosive salt will be distinguishable fromuntreated salt.

After the cathodic passifier solution is mixed with the salt, the moistsalt may be dried to remove the excess moisture present therein. Thesalt may be heated in a suitable oven or may be stored for a period oftime in a storage of low humidity. Regardless of the particular methodof drying selected, the anti-caking agent prevents caking of the saltand a granular free flowing salt of substantially improvedanti-corrosive characteristics is obtained.

It is apparent that other manners of preparing the anti-corrosive saltare available to those skilled in the art. In this connection, it ispossible to spray the salt with an aqueous solution of both the anodicpassifier and cathodic passifier, or to add the cathodic passifier indry form and spray on the anodic passifier, or to add all the chemicalsin a dry form.

In a specific embodiment of the manufacture of an anti-corrosive salt,tons of rock salt, 200 pounds of sodium and 100 pounds of sodiumferrocyanide are intimately mixed together, as by tumbling, in orderthat the sodium chromate and sodium ferrocyanide are intimatelydistributed through out the salt. 1,000 pounds of N-coconut-1,3propylene diamine diacetate in a 20 percent water solution are sprayedonto the salt mixture through a metering spray nozzle. The salt istumbled and mixed during and after being sprayed in order to distributethe fatty diamine salt and dye substantially throughout the salt. About1 to 20 pounds of Water per ton of salt are added to the sailt mixtureduring the spraying operation and the salt is allowed to dry in a warmstorage area of low humidity in order to allow moisture to evaporatefrom the salt. The presence of the sodium ferrocyanide anti-caking agentprevents caking of the moistened salt.

The salt product obtained is granular and free flowing in nature. Thecombined anodic passifier and cathodic passifier are intimatelydistributed upon the surface of each of the salt granules. When brine oran aqueous solution of the salt is present on :a roadway or in contactwith metal equipment, a metal surface in contact with the aqueous saltsolution is substantially protected from corrosion by the presence ofthe sodium chromate anodic 7 passifier and the N-coconut-l,3 propylenediamine di acetate cathodic passifier.

The following tables illustrate certain specific embodiments of theinvention described, and substantiate the improved corrosion resistanceobtained in an aqueous halide salt solution containing an anodicpassifier and a cathodic passifier.

In each of Tables I to IX the test procedure is carried out according tothe following.

Cold-rolled steel panels, similar in composition to those employed inthe fabrication of automobile bodies, two inches by three inches andabout 0.0343 inch thick, are employed as test panels. The mechanicallysheared edges of each of the panels are sanded smooth and the panels aredegreased with a 5:1 volume ratio of a carbon tetrachloride-benzenemixture. The panels are then cleaned with a detergent, rinsed thoroughlyin water and alcohol and dried in a desiccator under vacuum.

Three panels are employed to test each of the anticorrosive saltcompositions. The three panels are accurately weighed and are immersedin a 10 percent by weight sodium chloride brine solution containing thevarious anodic and cathodic passifiers having a volume of 1,000milliliters for a period of one hour. The panels are then air dried forsix hours and re-immersed in the same brine for an additional hour afterwhich the panels are Withdrawn from the brine and air dried for asixteen hour period. This twenty-four hour cycle test procedure isrepeated for two additional twenty-four hour periods to give a totaltest period of seventy-two hours. At the end of each twenty-four hourcycle one of the panels is removed TABLE I.RATE OF CORROSIONfQITIDPERCENT PROTECTION OF COLD-ROLLED STEEL IN 10 PERCENT from the brine.The corrosion products upon the surface of the panel are removed fromthe panel by cleaning with a brush and detergent. The panel is rinsedwith Water and dried quickly in a desiccator under vacuum. The driedpanel is weighed on an analytical balance to determine the weight lossof the panel due to corrosion.

The tests are conducted in a room having a temperature of 48 F. and arelative humidity of 98 percent. The brine solutions are thoroughlyagitated four times per day to insure equilibrium concentrationsthroughout.

The rate of corrosion is expressed in terms of percent weight loss ofthe panel and percent protection afforded to the panel by the corrosioninhibitors present in the brine as compared to control test panels whichare taken from the same metal stock and which are immersed in a tenpercent sodium chloride brine that is free of anticorrosive agents forthe same periods of time and under the same conditions as the panelsimmersed in the brine containing the anti-corrosive agents. Inasmuch asdilferent control panels are employed for various of the examples,slight variations in the results obtained are to be expected.Calculations of the percent weight loss and the percent protection areas follows:

Weight Loss of Panel Percent Weght Weight of Original Panel PercentWeight Loss of Test Panel Percent Weight Loss of Control Panel UEOUSSODIUM CHLORIDE BRINE 24 Hours 48 Hours 72 Hours Example Corrosioninhibitors, percent of brine {ficiant lgerctent 1635119181112 lgerctent'PVeroIent lgercent oss r0 ecoss ro ect. oss rotection tion tion 10.01875 N-tallow-1,3 propylene diarnine hydrochlo- 0.0378 97. 32 0. 158358.34 0.2743 58. 88

n e. 2 0.0125 N-coconut-1,3 propylene diamine acetate 0.0396 79. 610.1235 70. 0.2326 65. 99 3 0.011215 lg-eoconut-hii propylene diaminehydro- 0.0251 98.16 0.0746 80.37 0.1542 70.88

c on e. 4 0.001612 ilg-coconut-LE} propylene diamine hydro- 0.0254 98.140.0724 80.95 0.1469 77.98

c or e. I 0.006 N-coconut-L3 propylene diamine hydrobchloride. 0.033963.68 0. 0046 74.17 0. 1757 70.22

l0.006 MakonlO 0.004 N-ooconut-L3 propylene diamina hydro- 6- chloride.0.0395 57. 68 0. 1198 67. 28 0. 1855 68. 57

0.004 Makon 10 10.002 N-coeonut-1,3 propylene diamine hydro- 7 chloride.0. 0456 51. 22 0. 1556 57.49 0.2247 61.92

is-22 9 m l 6 -coconu ,3 propy ene iamine ace a e B 68 i gg 5 f da f a0.0324 55. 28 0.1142 68.80 0.2163 63.35

0 -ooconu -1, propy one am no iaceta e 9- .{g 88 gg I l a i af yif l 0.0328 64. 91 0. 1309 61.79 0. 2465 58. 23

l 2 -coconu propy one amino ace a e 10 fl ggg N 313 1 a af ii 0.037459.99 0. 1648 54. 98 0. 2493 57. 75

, -coconu propy one iamme ace a e..- 11 fliggg N Y f d i a 0. 0329 59.18 0. 0635 86. 57 0. 1352 84. 08

-coconutpropy one am no iacetate... 12- "m Makon 10 0.0176 94.09 0. 117978. 08 0. 318 57. 4 1s g;ggg ggggpgg g jf'f i fffffff I 0.1907 32.3 0.3017 44. 7 14 0.01 coconut trimethyl ammonium chloride. 0. 111 57.00.309 30. 72 0.467 28. 70] 1g nygggiieocomfi dimeflhyl ammoniumfihlorde- 0. 103 59. 88 0.285 36. 10 0.401 38. 78

coconu rimet y ammonium c ori e 10.005 dicooonut dimethyl ammoniumchloride... 095 03 252 5 460 77 0.01 dihydrogenated tallow dimethylammonium 17 chloride. 0.0942 62.9 0.2695 41. 2 0.390 44. 9

0.0;)1 hilako'n 10...];i i ..1 fi d [0.0 ta low rimet y ammon urnc ori c18 kg 81 t d gfi fg l gf a 0. 0760 68. 6 0.274 41.4 0.421 39.3

1 coconu ie ano enzy ammonium c ori e. 19 gl a 315 1 J 1 1 0.0440 v8. 40.1590 63.8 0.238 65.2

10. soya iet ano enzy ammonium c on e. 20 drop Make 10 0.0883 56. 50.223 49. 2 0. 425 37. 9

[0.01 v lauryl oxypropyl, trimethyl ammonium 21 chloride. 0.1155 43. 30.215 50. 9 0.353 48.3

,1 drop Makon 10 10.01 N-y cocomut oxypropyl-1,3 propylene dia- 22 mine.9.2182 22. 5 0.4308 21. 0

10001 Makon 10 0.01 N-'y coconut oxypropyl-1,3 propylene dia- 23 mine.0.0297 87. 7 0.117 74.9 0.203 70.7

10.001 Makon 10 0.01 N-y coconut oxypropyl-1,3 propylene dia- 24 minemonoacetate. 0.2131 24.3 0.3531 35.3

0.001 Makon 10 0.01 N-'y coconut oxypropy1-1,3 propylene diaminemonoacetate. 0.0485 81. 48 0.1487 69. 40 0.3232 53.80

0.001 Makon 10 TABLE 1.'Continued 24 Hours 48 Hours 72 Hours ExampleCorrosion inhibitors, percent of brine gftrclent lgerctent ggrclentgerctent gzrciant li erctent 058 ro ecoss r ecoss ro ection tion tion0.01 N-y coconut oxypropy1-1,3 propylene dia- 26 mine diacetate. 0.246112.6 0.4339 20. 4

0.001 Makon 0.01 N-- coconut oxypropyl-1,3 propylene dia- 27 mulediacetate. 0. 0560 78. 62 0. 1440 70. 42 0. 2919 58. 28

0.001 Makon 10 0.01 N-v coconut oxypropyl-dipropylene triamine 28 1(tiriacefiiti. 10 55 56.9 0.214 50. 1 0.3589 38.8

rop a 'on 0.01 N-lauryl-B aminopropionic acid 29 889 lgfi l m i d 0.047484.08 0.1679 68.79 0.234 68.7

aury -5 am oprop onic aci 30 Makom 19 I 0. 0372 85. 51 0.103 79. 5 0.17775. 7 31 -gilf (1mm N'lauryl'fi amimpmpmm" 0.0288 88.7 0.1052 78.20.1664 74.83

0. 01 partial sodium salt N-lauryl-B aminopropionic 32 oaggM k 0 0.068976.86 0.2052 61.85 0.224 62.2

a on 33 0.05 sodium N-eoconut-B amlnopropionate. 0.040 86.1 0.0926 82.40.147 81.7 34 0. 05 disqdium N-tallow-B iminodipropionate 0.045 84.40.1631 69.0 0.223 72.3

0. 01 sodium N-v octyl oxypropyl-B ammopro- 35 plonate. 0362 82. 00 0.1343 71. 72 0. 1905 74. 17

0. 001 Makon 10 1 0. 01 sodium N-y octyl oxypropyl-fl aminopro- 36pionate. 0.0319 85.4 0.0988 79. 0 0.1872 71.8

0. 001 Makon 10 .01 sodium N-y lauryl oxypropyl-B aminopro- 37 pionate.0. 0244 87.87 0. 0902 81.01 0. 1424 80. 69

0.001 Makon 10 0.01 sodium N W lauryl oxypropyl-B aminopro- 38 pionate.0.0332 85.8 0. 0816 82. 4 0.134 80.8

0.001 Makon 10 0. 01 disodium N-y octyl oxypropyl-B iminodipro- 39pionate. 0350 82. 60 0. 1391 70. 71 0.2570 65.15

0. 001Makon 10 0. 01 disodium N y octyl oxypropyl-fi iminodipro- 40pionate. 0. 0418 80.8 0.0945 79.9 0.2116 68.2

0.001 Makon 10 0. 01 disodium N-y lauryl oxypropyl-B iminodipro- 41pionate. 0.0366 83.29 0.1267 73. 32 0.1803 75.

0. 001 Makon 10 0. 01 disodium N-y lauryl oxypropyl-B iminodi- 42 0ggfrfimfitem 0.03165 86.5 0.0990 78.6 0.1534 78.0

a on 43 0.05 N-B soya amidoethyl-ethylene diam ine 0.1480 42.2 0.338130.0 0.4808 27.27 4 8:831 651F31123135113131213???is???; 51 we 46 284 m0. 05 N tall oil amidoethylethylene diamine. 0.0648 74. 7 0.2938 39.1 0.4963 24. 93 46 0. 05 N-fl Oleyl amidoethyl-ethanol amine- 0. 0713 72. 20. 2609 47. 2 0. 3451 47. 47 --{g g if fig gffff ff'ff fffi ffff ff I 0.0503 as. 10 0.1824 00. 09 0. 361 51.6 48 $.35i-etiganolg-lfiepiagecenyll imigazolli neu 0.0768 52. 59 0.334 41.30.2911 58.60

. -e ano ep 0 eceny 11111 are me. 49 Makon 10 0. 0731 75.44 0. 223158.52 0. 345 53.6

Table I illustrates tests performed with various cathodic passifiers asthe sole corrosion inhibitor. Generally, the presence of cathodicpassificrs alone does not provide suflicient protection againstcorrosion. Further, it is noted that in most instances the percentprotection afforded by a cathodic passifier decreases over the period of24 hours to 72 hours, indicating that the galvanic barrier establishedby the film of cathodic passifier is slowly washed away.

Table II illustrates similar tests carried out wherein the soleanti-corrosive agent present is an anodic passifier. The sodium chromateand potassium dichromate anodic passifiers provide increased percentprotection from 24 hours to 72 hours, while the sodium nitrite anodicpassifier provides decreased protection over the same period. It isbelieved that this difference occurs due to the solubility of theammonia reduction product of the sodium nitrite anodic passifier whichis removed from the TABLE IL-RATE OF CORROSION AND PERCENT PROTECTION OFCOLD-ROLLED STEEL IN 10 PERCENT AQUEOUS SODIUM CHLORIDE BRINE 24 Hours48 Hours 72 Hours Example Corrosion inhibitors, percent of brine PercentPercent Percent Percent Percent Percent Wt. loss Protcc- Wt. lossProtec- Wt. loss Protectiou tion tion 50 0.01 sodium chromate 0.1332 62.45 0. 1900 69. 51 0. 2362 74. 09 0.01 potassium dichromate 0.1051 70.760.0951 84.79 0.1305 85.69 52 0.01 sodium nitrite 0. 2366 35. 19 0. 441729. 35 0. 7794 14. 51

li ll surface of the metal panels and is not present in the coating ofinsoluble corrosion products that is formed.

rosion. Examples 57 and 58 were carried out utilizing Triton X-200, ananionic surface active agent, as a dis- TABLE 1II.-RATE OF CORROSION ANDPERCENT PROTECTION OF COLD-ROLLED STEEL IN 10 PERCENT AQUEOUS SODIUMCHLOR'IDE BR-INE 24 Hours 48 Hours 72 Hours Example Corrosioninhibitors, percent of brine Percent Percent Percent Percent PercentPercent Wt. loss Protec- Wt. loss Protec- Wt. loss Protection tion tion0.01 sodium chromate H 53 '01 g-1 3 propylenediamine 0163 19 0275 11 0.0400 94. 77

0.01 sodium 0 romate 54 "{0005 N-cooonut-LB propylene diarnine diacetate0185 O3 0301 65 57 0.01 sodium chromate 55 "{001 N-coconut-L3 propylenediamine diacetate 0. 0189 74. 83 0. 0269 02, 94 0, 0274 11 0.001 Makon0.01 sodium chromate 56 "i001 N-eoconut-1,3 propylene diamine diaeetate0. 0189 01. 33 0. 0334 e2. 02 o, 03 2 94 59 0.001 Makon 10 0.01 sodiumchromate 57 {0.01 N-coeonut-L3 propylene diamine diacetate 0. 0449 73.67 0.1099 7s. 90 0,1802 75, 90

0.01 Triton X-200 0.01 sodium chromate .58 "{001 N-coc0nut-1,3 propylenediarnine diacetate 0. 0370 S0. 47 0. 1304 74. 96 0,1700 78. 21

0.001 Triton X-200 0.01 sodium chromate 59 {0.01 Ncoconut-l,3 propylenediamine diaeetate 0. 0176 90. 86 0. 0306 94. 49 0, 0709 92 1 0.001 Makon10 0.01 sodium chrorqatm 1 E.i t {t 0.01 N-coconut-l, propy ene r am heriace a e.

50 0.001 Makon 10 0. 0061 95. 72 0.0186 06. 98 0. 0195 97.94

Dy 0.01 sgglinrn chioinaatm 0.005 -coconu O 61 04005 Makon l0 0. 0 6895.3 0. 0175 07.10 0. 0020 07,88

Dye 0.01 sodium ehrom 1- B2 0.01 N-eoconut-l,3 propy 0. 0251 93. 02 0.0403 93. 0. 0576 93.68

0.001 Makon l0 Table III illustrates the anti-corrosive properties of asodium chromate anodic passifier and alkyl diamine and alkyl triaminecathodic passifiers. It can be seen that each of the examples in Table111 provides excellent corrosion protection, and in this connection, allof the examples in Table IV with the exception of Examples 57 and 58provide in excess of 90 percent protection against corpersing agent forthe fatty acid diarnine salt, and it is postulated that the presence ofthis particular dispersing agent in some manner alfected the filmforming properties of the fatty acid diamine salt and thereby reducedthe percent protection provided by the anticorrosive salt C0111-position.

TABLE IV. RATE OF CORROSION AND PERCENT PROTECTION OF COLD-ROLLED STEELIN 10 PER- CENT AQUEOUS SODIUM CHLORIDE BRENE Example 53 3 0.01 sodiumnitrite 0.01 N-coeonut-l, 3 propylene diamine diaeetate loom Makon 10%0.01 sodium nitrite 0.01 Tr ton X-200.

0.01 sodium nitrite. l 0.01 N-coeonut-l, 3 prop 0.005 Triton X-200 {0.01sodium nitrite 0.01 N-coconut-l, 3 propyl ne 0.001 Triton X-200 0.01sodium nitrite 67 0.01 N-coeonut-1,3 propylen i 0.001 Makon 10 Y 002Sodium nitrite 0.01 N-coconut-1,3 propylene lDye E001 sodium nitrite 690.001 Makon 10 0.01 sodium nitrite "10.001 Makon 10 LDye 0.01 sodiumnitrite i 0 005 Malron 10 Dye 0.01 sodium nitrite 0.00025 Makon 10 Dye e0.01 sodium nitrite 74 "i001 N-coconut-l, 3 propylene 0.001 Makon 10Corrosion inhibitors, percent of brine 0.01 N-coconut-L3 propylenediamine diacetate iamlne diacetate 0.001 Makon 10 .01 N-coconut-l,3propylene diamine diacetate.- 0.05 sodium ierroeyanide 0.01 N-eoconut-L3propylene triamlne triaeetate 0.005 N-eoeonut-3,1 propylene triaminetriaeetate:

0.0025 N-eoeonut-l, 3 propylene triamlne triacetate 24 Hours 48 Hours 72Hours Percent Wt. loss Percent Protection Percent Wt. loss Percent Wt.loss Percent Protection Percent Protection Illlllllllll Table IVillustrates the anti-corrosive properties of a to the use of the anodicpassifiers or cathodic passifiers sodium nitrate anodic passifier andalkyl diamine and by themselves.

TABLE V.-RATE F CORROSION AND PERCENT PROTECTION OF COLD-ROLLED STEEL INPERCENT AQUEOUS SODIUM CHLORIDE BRINE 24 Hours 48 Hours 72 Hours ExampleCorrosion inhibitors, percent of brine Percent Percent Percent PercentPercent Percent Wt. loss Protec- Wt. loss Protec- Wt. loss Protectiontion tion 77 0.01 sodium chromate 0.001 Makon 10 78 {0.01 dicoconutdimethyl ammonium chloride. 0.01 sodium chromate- {0.005 coconuttrimethyl ammonium chloride.

{0.01 dlcoconut dimethyl ammonium chloride- -1} 0.006 dicoconut dimethylammonium chloride 0.01 sodium chromate 0.005 coconut trimethyl ammoniumchlorid 80 0.005 dicoconut dimethyl ammonium chloride-- 0. 050 80. 470.103 76. 90 0. 164 74. 96

0.01 sodium chromate chloride.

{0.01 dihydrogenated tallow dimethyl ammonium 81 001 sodium chromate 0.0475 70. 68 0.074 87. 0

0:01 dihydrogenated tallow dimethyl ammonium 82 chloride.

0.01 sodium chromate 0495 7 0.01 Makon 10 {0.01 tallow trimethylammonium chloride.

84 0.01 sodium chromate 0.001 Makon 10 0.01 tallow trimethyl ammoniumcholrlde.

85 0.01 sodium clliromate 0.001 Makon 10 0.01 coconut diethanol benzylammonium chloride. 87 0.01 sodium chromate 0. 0342 83. 2

0.01 soya diethanol benz 88 0.01 hromate 0. 0405 80.1

1 drop Makon 10 0.01 'y-lauryl oxyprop 89 chloride.

1 drop Makon 10 0.01 dihydrogenated tallow dimethyl ammonium 91 {0:01tallow trimethyl ammonium chloride.

.01 sodium nitrite 0.001 Makon 10 {0.01 coconut diethanol benzylammonium chloride} 92 0.01 sodium nitrite 1 drop Makon 10 {0.01 soyadiethanol benzyl ammonium chloride 93 0.01 sodium nitrite 1 drop Makon10 {0.01 'y lauryl oxypropyl trimethyl ammonium} 94 chloride. 0.01sodium nitrite 1 drop Makon 10 alkyl triamine cathodic passifiers. Thepercent protection obtained by the use of the combination of theseanticorrosive agents in aqueous sodium chloride solutions is in excessof the percent protection obtained using previously known anti-corrosiveagents. Although the percent protection obtained is slightly lower thanthe percent protection obtained when an alkali metal chromate ordichromate is employed as the anodic passifier, substantially improvedresults are obtained when compared Table V illustrates the corrosionprotection of sodium chromate and sodium nitrite anodic acifiers andalkyl quaternary ammonium cathodic pacifiers. It can be seen thatquaternary ammonium compounds which contain an alkyl radical of from 8to 24 carbon atoms and mixtures thereof function as cathodic passifiers,and when combined with an anodic passifier provide improved protec- 75tion against corrosion in aqueous salt solutions.

TABLE VI.RATE OF CORROSION AND PERCENT PROTECTION OF COLD-ROLLED STEELIN PERCENT AQUEOUS SODIUM CHLORIDE BRINE Example {0.01 N w coconutoxypropyl-1,3 propylene diarnine 05 {0.01 N-v coconut oxypropyl1 06[0.01 N-v coconut QXypmpyI-dipropylcHetriamine 104 0.01 N-v coconutoxypropy ".24 Hours 48 Hours 72 Hours Wt. loss Percent ProtectionPercent Wt. loss 0.01 sodium chromate 0.001 Makon 10 0.01 sodiumchromate- 0.001 Makon 10 0.005 N--y coconut oxypropyl-1,3 propylenediamine 0.01 sodium chromate monoocetate. 0.01 sodium chromate. 0.001Makon 10---. 0.01 N-v coconut oxypr monoacetate.

0.01 sodium e11romete 0.001 Makon 10 0.005 N-y coconut oxypropy minemonoacetate.

0.01 sodium chromate 0.001 Mokon 10 0.01 N-w coconut oxypropy {0.01N-coconut oxypropyl-1,3 propylene diaminej.

0.001 Melon 10 triacetate. 0.01 sodium chromate 1 drop Makon 10 0.01sodium nitrite monoacetate.

diacetate. 0.01 sodium nitrite. 0.001 Makon l0 medium. 1

triacetote. 0.01 Sodium nitrite 0. 0502 1 drop Makon 10 PercentProtection Percent Wt. loss TABLE VIL-RATE OF CORROSION AND PERCENTPROTECTION OF COLD-ROLLED STEEL IN .10 PERCENT AQUEOUS SODIUD/I CHLORIDEBRINE Example {0.01 N -lauryi-B aminopropionic acid 109 {0.01 N-iouryl-Baminopropionic acid" 110 111 01001 Makon 10 0.01 sodium nitnt 110 24Hours 48 Hours 72 Hours Corrosion inhibitors, percent of brine PercentWt. loss Percent Protection Percent Wt. loss 0.01 sodium chr0mate 10.560!) 0.001 Makon 10 0.01 sodium chromatc 0.001 Makon 10 0.01N-Iauryl-fl aminopropionic acid" 0.01 sodium chromate-.-

0.01 pirtiel sodium salt N-lauryl-fl aminopropionic aci 0.01 sodiumchromate 0.001 Makon l0 0.01 P51101211 sodium salt N-iauryi-Baminopropionic aci 0.01 sodium chromate 0.001 MakOIl 10 0.01 partialsodium acid. 0.01 sodium chromate- 0.001 Mokon 10 0.01 sodiumN-coconut-B a 0.01 sodium chromate 0.001 Makon 10 0.01 sodiumN-coconut-fl aminopropionatc. 0.01 sodium chromete.--

0.0835 0.01 disodium N-tallow-fi? 1m1uodipr0pi0natc- 0.01 sodiumchromate.-- 0.001 Makon 1O 0.01 N-leuryl-B aminopropronrc acid 0.01pirtial sodium salt N-lauryl-B aminopropionic acr 120 {0.01 sodiumnitrite 0.001 Makon 10 Percent Protection Percent Wt. loss PercentProtection Table VI illustrates the improved resistance to corrocentprotection obtained when sodium nitrate is used as sion in aqueous saltsolutions provided by sodium chrothe anodic passifier is believed to bedue to the fact that mate and sodium nitrate anodic passifiers incombination the ammonia reduction product is soluble and is not rewithN-y alkyl oxypropyl-diamines and triamines and tained at the surface ofthe metal plate. salts thereof. As discussed above, the slightly lesserper- 5 TABLE VIIL-RATE OF CORROSION AND PERCENT PROTECTION OFCOLD-ROLLED STEEL IN 10 PER- CENT AQUEOUS SODIUM CHLORIDE BRINE 24 Hours48 Hours 72 Hours Example Corrosion inhibitors, percent of brine PercentPercent Percent Percent Percent Percent Wt. loss Ptotec- Wt. lossProtec- Wt. loss Protection tion tion 0.01 sodium N-q octyl oxypropyl-Baminopropio- 0.01 sodium chromate 0.001 Makon 10 {0.01 sodium N-7 octyloxypropyl-B aminopropionate. om sodium chmmate 0.0199 90.9 0.0573 87.80.0656 90.1

0.001 Makon 10 0.01 sodium Nw lauryl oxypropyi-fl aminopropio- 1'18, 12sQmsodium chromate 0.0239 88.12 0.0302 92.38 0. 0504 92.35

0.001 Makon 10 0.01 sodium N-qr lauryl oxypropyl-fi aminopropiona e.

124 m Sodium ehmmate 0. 0210 91.0 0.0583 87.4 0. 0892 87. 2

0.001 Makon 10 0.01 disodium N-v oetyl oxypropyl-B iminodipro- 195pionate.

0.01 sodium chromate 0. 0216 89.26 0. 0366 92. 29 0. 0502 93. 19

0.001 Makon 10 0. 01 disodium N-y oetyl oxypropyifi iminodi- 1 126propionate.

0.01Sodmmehmmate 0.0280 87.2 0.0009 85.2 0. 0011 86.2

0. 001 Makon 10 {0. 01 disodium N- lauryl oxypropyi-fi iminodipropionate127 Q01 Sodium chromate 0.0118 94. 13 0.0408 91. 41 0.0593 91.96

0. 001 Makon 10 0. 01 disodium N--ylau.ryloxypropy1-B iminodi- 1 128propionate.

"""" 0. 01 sodium ehromate.

0. 001 Makon 10 {0. 01 sodium N-q octyl oxypropyl-B aminopro- 129pionate 01 Sodium mmte 0.0275 87. 4 0. 0824 82. 5 0.1487 77. 6

0. 001 Makon {0. 01 sodium N-'y lauryl oxypropyl-fi aminopropionate. 0.01 sodium nitrite.

0. 001 Makon 10 {0. 01 disodium N--y ootyi oxypropyl-fliminOdipropionate 0.01 sodium nitrite.

0. 001 Makon 10 {0. 01 disodium N-y Iauryl oxypropyl-fliminodipropionate 0.01 sodium nitrite.

0. 001 Makon 10 TABLE IX.RATE OF CORROSION AND PERCENT PROTECTION OFCOLD-ROLLED STEEL IN 10 PER- CENT AQUEOUS SODIUM CHLORIDE BRINE 24 Hours48 Hours 72 Hours Example Corrosion inhibitors, percent of brine PercentPercent Percent Percent Percent Percent Wt. loss Pibtec- Wt. lossPzotec- Wt. loss Protecon on ion 0.001 Makon 10 0.01 N-B soyaamidoethyl-ethylene diarnine.

134 0.01 sodium chromate 0.0351 78. 33 0.087 84. 7 0, 0358 3180 0.001Makon 10 {0.01 N-B tall 011 amidoethyl-ethylene diamine. 135

0.01 sodium chromnte 0.0515 79. 9 0. 0994 79. 4 0. 1432 78. 34 0.001Makon 10 0.01 N-fi tall oil amidoethyl-ethylene diannne.

136 0.01 sodium chromate 137 0.01 sodium chromate 0. 0256 90.0 0.088181. 8 0. 1674 74, 3

0.001 Makon 10 0.01 N-B oieyl amidoethyi-ethanol am 138 0.01 Sodiumchromate 0.0320 80. 0. 083 86.1 0. 1428 79. 09

139 {0.01 sodium chromate 0.001 Makon 10 Tables VII, VIII and IX aresimilar to the previous tables and illustrate the anti-corrosiveproperties of additional cathodic passifiers in combination with sodiumchromate and sodium nitrate anodic passifiers, Table VII illustrates theprotection afforded by N-alkyl-fi aminopropionic acids and dipropionicacids in combination with an anodic passifier and Table VIII illustratesthe protection afforded by N-y alkyl oXypropyl-fi arninopropionic acidsand dipropionic acids in combination with an anodic passifier.

Table IX illustrates the corrosion protection afforded by N-fl alkylamidoethyl-ethylene diamines, N-fi alkyl amidoethyl-ethanol amines andl-ethanol, 2-alkyl imidozoline in combination with a sodium chromateanodic passifier.

Table X illustrates the improved anticorrosive characteristics of thedescribed anticorrosive salt in actual field tests. Cold-rolled steelpanels, similar in composition to those employed in the previous tables,three inches wide by six inches long and having a 16 gauge thickness areemployed in each of the field tests. The mechanically sheared edges ofthe panels are sanded smooth and the surfaces of the panels are lightlysanded. The panels are then degreased with a five to one solution ofcarbon tetrachloride and benzene. The panels are cleaned with adetergent, rinsed with water and dried in a desiccator under vacuum. Thepanels are attached vertically to the fenders of various cars in amanner so that the panel is parallel to the tire tread.

A blacktop area of approximately 7,000 square feet is used for eachtest. 60 pounds of salt are evenly distributed over the test area eachday and the test area is sprinkled with water twice each day that itdoes not rain or snow. Cars are driven through the test area forapproximately three miles twice each day and each car is parked in theopen between each test run. The panels attached to the cars driventhrough the areas sprinkled with salt containing an anodic passifier anda cathodic passifier in accordance with the present invention arecompared against like panels attached to cars driven through areascontaining untreated rock salt. The percent weight loss and percentprotection are determined in the manner described above.

TABLE X.-CORROSION OF COLD-ROLIJED STEEL PANELS DURING ROAD TEST PercentPercent Example Days Corrosion inhibitors, weight protecdriven percentby weight of salt loss, tion average average 0.1 sodium nitrite M 7 0.1N-w coconut-1,3 propyl- 0.5068 59. 57 ene diamine diacetate.

0.1 sodium nitrite 141 11 0.1 N y coconut-1,3 propyl- 0. 5809 60. 72

ene diamine diacetate. 0.1 sodium nitrite 142 0.1 N-w coconut-1,3propyl- 0.5281 57. 07

l ene diamine diacetate. 10.1 sodium nitrite 143 14 ,0.1 Na coconut-1,3propyl- 0. 7867 52. 33 L ene diamine diacetate. 0.1 sodium nitrite 144 7i 0.1 N-'y coconut-1,3 propyl- 0.5175 58. 33

ene diamine diacetate. 0.1 sodium nitrite 145 14 0.1 N w coconut-1,3propyl 0.6838 56. 29

ene diamine diacetate.

Table X illustrates the substantially improved corrosion protectionobtained under simulated driving conditions with salt treated with ananodic pacifier and a cathodic pacifier. Over periods of up to 14 days,salt containing an anodic passifier and a cathodic passifier providedfrom 50 to 60 percent protection when compared to salt which did notcontain a corrosion preventative agent.

Identical road tests were also carried out using sodiumhexametaphosphate as the sole anti-corrosive agent in the saltcomposition. The sodium hexametaphosphate treated salt provided about 30percent protection against corrosion after seven days as compared tountreated rock salt. However, after fourteen days, the sodiumhexametaphosphate treated salt was totally ineffective and provided 0percent protection against corrosion. However, salt containing a sodiumnitrite anodic passifier and a N-coconut-1,3 propylene diamine diacetatecathodic passifier provided greater than 50 percent protection againstcorrosion. The percent protection afforded by the salt containing asodium nitrite anodic passifier and a N-coconut-1,3 propylene diaminediacetate cathodic passifier remained substantially the same from theseventh day to the fourteenth day while the protection afforded by salttreated with sodium hexametaphosphate dropped from 30 percent protectionto substantially no protection.

It can be seen that a salt composition has been provided which hassubstantially increased protection against corrosion in an aqueoussolution. The salt composition provides increased protection againstcorrosion over an extended period of time and the anti-corrosive agentsare not diluted or washed from the metal surface during extendedexposure to moisture and/or driving conditions. Further, the presentinvention provides an improved combination of anti-corrosive agentswhich, in an aqueous solution, provide increased protection againstcorrosion in the presence of corrosive salts.

Although certain features of the invention have been set forth withparticularity in order to describe the invention, other alternativeembodiments within the skill of the art are contemplated.

Various of the features of the invention are set forth in the followingclaims.

What is claimed is:

1. A salt composition for de-icing having improved corrosion inhibitingproperties in respect to automobile bodies and trim comprising, a watersoluble sodium or calcium de-icing salt, a minor but effective amount ofan anodic passifier selected from the group consisting of alkali metalchromates and alkali metal nitrites, and a minor but effective amount ofat least one cationic surface active agent cathodic passifier selectedfrom the group consisting of compounds of the formulae Iq Ho c xrp-nwhere:

R=an alkyl radical of from 8 to 24 carbon atoms R =hydrogen or a shortchain alkyl radical of from 1 to 6 carbon atoms R =hydrogen or a shortchain alkyl radical of from 1 to 6 carbon atoms R =a short chain alkylradical of from 1 to 6 carbon atoms X =a salt forming radical Z=an aminoor hydroxyl radical m=2 to 10 12:1 to 3 and the sum of 0 and p is 4 r=0or 1 and the sum of q and r is 2 and soluble salts thereof.

2. A salt composition for de-icing having improved corrrosion inhibitingproperties in respect to automobile bodies and trim comprising, a watersoluble sodium or calcium deicing salt, a minor but eifective amount ofan alkali metal chromate anodic passifier, and a minor but effectiveamount of at least one cationic surface active agent cathodic passifierselected from the group consisting of compounds of the formulae RNH(CH2) nN\ RNH(CH2) NH (CH2) mN\ RO(CH2)3NH(CH2)11N R0 (CH2) aNH (CH1) NH(CH9) mN\ RN[HI(CH2)2CO OHh (6) RH(CH2)3NHI[(CH2)flCOOH] [RO(CH2)3]QN+ X(9) (HO CHzCHg):

+ C H2 co s, X-

RCNHKCHQ) 2NH (CH2)2Z N (CH :0 H

C'HsC 2 12 Koontz where p=1 to 3 and the sum of o and p is 4 q=1 or 2r=0 or 1 and the sum of q and r is 2 and soluble salts thereof.

3. A salt composition for de-icing having improved corrosion inhibitingproperties in respect to automobile bodies and trim comprising, a watersoluble sodium or calcium de-icing salt, a minor but eifective amount ofan alkali metal nitrite anodic passifier, and a minor but effectiveamount'of at least one cationic surface active agent cathodic passifierselected from the group consisting of compounds of the formulae R=analkyl radical of from 8 to 24 carbon atoms R =hydr0gen or a short chainalkyl radical of from 1 to 6 carbon atoms 7 R -=hydrogen or a shortchain alkyl radical of from 1 to 6 carbon atoms R =a short chain alkylradical of from 1 to 6 carbon atoms 1 23 X=a salt forming radical =anamino or hydroxyl radical n=2 to 10 m=2 to 10 :1 to 3 2:1 to 3 and thesum of o and p is 4 11:1 or 2 r=0 or 1 and the sum of q and r is 2 andsoluble salts thereof.

4. A salt composition for de-icing having improved corrosion inhibitingproperties in respect to automobile bodies and trim comprising, a Watersoluble sodium or calcium halide de-icing salt, at least about 0.05percent by weight of said salt of an alkali metal chromate ordichromate, and at least about 0.01 percent by weight of said salt of acompound of the formula R1 RNHwrmnN R2 and soluble salts thereof, whereR=an alkyl radical of from 8 to 24 carbon atoms, R and R =hydrogen or ashort chain alkyl radical of from 1 to 6 carbon atoms, and n=2 to 10.

5. A salt composition for de-icing having improved corrosion inhibitingproperties in respect to automobile bodies and trim comprising, a watersoluble sodium or calcium de-icing salt, a minor but effective amount ofan alkali metal chromate or dichromate anodic passifier, and a minor buteffective amount of at least one cationic surface active agent cathodicpassifier selected from the group consisting of compounds of theformulae R1 RNH(CHg)uNH(CH2)mN R: where R=an alkyl radical of from 8 to24 carbon atoms, R and R =hydrogen or a short chain alkyl radical offrom 1 to 6 carbon atoms, 11:2 to 10, and m=2 to 10.

6. A salt composition for de-icing having improved corrosion inhibitingproperties in respect to automobile bodies and trim comprising, a watersoluble sodium or calcium de-icing salt, a minor but effective amount ofan alkali metal chromate or dichromate anodic passifier, and a minor buteffective amount of at least one cationic surface active agent cathodicpassifier selected from the group consisting of compounds of the formulaRt RO(CHz)aNH(CHa)nN where R=an alkyl radical of from 8 to 24 carbonatoms, R, and R =hydrogen or a short chain alkyl radical of from 1 to 6carbon atoms, and n=2 to 10.

7. A salt composition for de-icing having improved corrosion inhibitingproperties in respect to automobile bodies and trim comprising, a watersoluble sodium or calcium de-icing salt, a minor but effective amount ofan alkali metal chromate or dichromate anodic passifier, and a minor buteffective amount of at least one cationic surface active agent cathodicpassifier selected from the group consisting of compounds of the formulaR1 R0(CHa)aNH(CHa)nNH(CHn)mN R: where R=an alkyl radical of from 8 to 24carbon atoms, R and R =hydrogen or a short chain alkyl radical of from 1to 6 carbon atoms, n=2 to 10, and m=2 to 10.

8. A salt composition for de-icing having improved corrosion inhibitingproperties in respect to automobile bodies and trim comprising, a watersoluble sodium or calcium de-icing salt, a minor but effective amount ofan alkali metal chromate or dichromate anodic passifier,

24 and a minor but effective amount of at least one cationic surfaceactive agent cathodic passifier selected from the group consisting ofcompounds of the formula annmcnp coom where R=an alkyl radical of from 8to 24 carbon atoms, q=1 or 2, r=0 or 1 and the sum of q and r is 2.

9. A salt composition for de-icing having improved corrosion inhibitingproperties in respect to automobile bodies and trim comprising, a watersoluble sodium or calcium de-icing salt, a minor but effective amount ofan alkali metal chromate or dichromate anodic passifier, and a minor buteffective amount of at least one cationic surface active agent cathodicpassifier selected from the group consisting of compounds of the formulawhere R=an alkyl radical of from 8 to 24 carbon atoms, q=1 or 2, r==0 or1 and the sum of q and r is 2.

10. A salt composition for de-icing having improved corrosion inhibitingproperties in respect to automobile bodies and trim comprising, a Watersoluble sodium or calcium de-icing salt, a minor but effective amount ofan alkali metal chromate or dichromate anodic passifier, and a minor buteffective amount of at least one cationic surface active agent cathodicpassifier selected from the group consisting of compounds of the formulawhere R=an alkyl radical of from 8 to 24 carbon atoms, R =a short chainalkyl radical of from 1 to 6 carbon atoms, X =a salt forming radical,0:1 to 3, p=1 to 3, and the sum of 0 and p is 4.

11. A salt composition for de-icing having improved corrosion inhibitingproperties in respect to automobile bodies and trim comprising, a Watersoluble sodium or calcium de-icing salt, a minor but effective amount ofan alkali metal chromate or dichromate anodic passifier, and a minor buteffective amount of at least one cationic surface active agent cathodicpassifier selected from the group consisting of compounds of the formula0 2) iilo v X- where R=an alkyl radical of from 8 to 24 carbon atoms, R=a short chain alkyl radical of from 1 to 6 carbon atoms, X=a saltforming radical, 0:1 to 3, 12:1 to 3, and the sum of 0 and p is 4.

12. A salt composition for de-icing having improved corrosion inhibitingproperties in respect to automobile bodies and trim comprising, a watersoluble sodium or calcium de-icing salt, a minor but effective amount ofan alkali metal chromate or dichromate anodic passifier, and a minor buteffective amount of at least one cationic surface active agent cathodicpassifier selected from the group consisting of compounds of the formulawhere R=an alkyl radical of from 8 to 24 carbon atoms and X =a saltforming radical.

13. A salt composition for de-icing having improved corrosion inhibitingproperties in respect to automobile bodies and trim comprising, a watersoluble sodium or calcium de-icing salt, a minor but effective amount ofan alkali metal chromate or dichromate anodic passifier, and a minor buteffective amount of at least one cationic surface active agent cathodicpassifier selected from the group consisting of compounds of the formulawhere R=an alkyl radical of from 8 to 24 carbon atoms and Z=an amino orhydroxyl radical.

14. A salt composition for de-icing having improved corrosion inhibitingproperties in respect to automobile bodies and trim comprising, a watersoluble sodium or calcium de-icing salt, a minor but elfective amount ofan alkali metal chromate or dichromate anodic passifier, and a minor buteffective amount of at least one cationic surface active agent cathodicpassifier selected from the group consisting of compounds of the formulawhere R=an alkyl radical of from 8 to 24 carbon atoms. 15. A saltcomposition for de-icing having improved corrosion inhibiting propertiesin respect to automobile bodies and trim comprising, a water solublesodium or calcium de-icing salt, a minor but effective amount of analkali metal chromate or dichromate anodic passifier, and a minor buteffective amount of at least one cationic surface active agent cathodicpassifier selected from the group consisting of compounds of the formulaCHzCHzZ where R=an alkyl radical of from 8 to 24 carbon atoms and Z=anamino or hydroXyl radical.

16. A method of treating a de-icing salt for melting ice and snow toimprove the anti-corrosive properties thereof comprising, admixing witha sodium or calcium de-icing salt at least about 0.05 percent by weightof said salt of an anodic passifier selected from the group consistingof alkali metal chromates, and alkali metal nitrites and at least about0.01 percent by weight of said salt of at least one cationic surfaceactive agent cathodic passifier selected from the group consisting ofcompound of the formulae RHKCHMCOOHI and soluble salts thereof, at leastone of said anodic passifier and said cathodic passifier being appliedto said salt in the form of an aqueous solution thereof, anddistributing said anodic passifier and said cathodic passifiersubstantially uniformly throughout said salt References Cited UNITEDSTATES PATENTS 1/ 1966 Standish et a1. 252- OTHER REFERENCES TechnicalBulletin, Duomeens, Armour Industrial Chemical Co., 1958, pp. 3, 9.

LEON D. ROSDOL, Primary Examiner.

S. D. SCHWARTZ, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,384,590 M 21, 1968 Russell A. Eversole et al.

It is certified that error appears in the above identified patent andthat said Letters Patent are hereby corrected as shown below:

Column 2, lines 19 to 22, the formula should appear as shown below:

RNH(CH N same column 2, lines 25 to 28, the formula should appear asshown below:

same column 2, lines 30 to 34, the formula should appear as shown below:

R0 (CH2) NH(CH N same column 2, line 42, "RNH[CH COOK-Il should read RNH(CH COOI-I] line 45, "R0(CH NH (CH COOH] should read RO (CH NI-I (CHCOOH] Column 3, between lines 20 and 21, insert m 2 to 10 Column 5, line50, "manufatured" and "dray should read manufactured and dry Column 6,line 51, after "sodium" insert chromate Columns 7 and 8, TABLE I, secondcolumn, line 45 thereof, "cocomut" should read coconut same columns,same table, fifth column, line 22 thereof, "9. 2182" should read O.2l82Columns 9 and 10, TABLE II, sixth column, line 1 thereof, "69.51" shouldread 69. 61 Columns 11 and 12 TABLE IV, first column, line 30 thereof,"3,1" should read 1,3 same table, eighth column, line 11 thereof,"54.24" should read 54.34 same table, third column, line 12 thereof,"0.039" should read 0.0739 Columns 13 and 14 TABLE V, second column,line 29 thereof, "0.01 Makon 10" should read 0.001 Makon l0 same table,seventh column, line 10 thereof, "0.0389 should read 0.0839 Columns 15and 16, TABLE VI second column, line 7 thereof, after "diamine" cancel"1''; same table, seventh column, line 3 thereof, 0. 0830" should read0.0803

Column 19, line 4, "nitrate" should read nitrite I Column 20, lines 39to 57, formulas l to 6, should appear as shown below:

RNH(CI-I N RNH(CH NH(CI-I N R0 (CH2) m; (011 u R0 (CH2) 1m (CH NH (CH NColumn 21, formula (5) should appear as shown below:

RNI-I [(.CH coom same column 21, formula (6) should appear as shownbelow:

R0 (CH2) NH (CH2) coon] Column 22, formula (5) should appear as shownbelow:

RNH (CH COOH] 8 same column 22, formula (6) should appear as shownbelow:

Column 24, line 4, "RNHr" should read RNH line 16, "NHr [CI-I shouldread- H (CH lines 44 to 46, the formula should appear as shown below:

[RO(CH N+ xcolumn 25, lines 11 to 14, the formula should appear as shownbelow:

N(CH OH CH CH same column 25, line 58, "RI-IE" should read RNH Column26, line 1,

"NH[" should read NH E line 28, after "1" insert to Signed and sealedthis 24th day of March 1970.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. WILLIAM E. SCHUYLER, JR. Attesting OfficerCommissioner of Patents

